Is joule thief circuit gets overunity?

[Void]

As a rule of thumb when measuring the input and "output" power of a device, unless the chosen output component (LED in this case) power is easily exceeding the measured input power, one must individually-measure ALL the circuit components (excluding the source) and sum them all to compare to the input power.

If the sum total of all the output components' power is greater than the input power, then you may have something.

In the case of Lawrence's JT, the input power is the source or battery power.

Each "output" component to be measured for power is listed below:

1) Input CSR resistor
2) 1k base resistor
3) base inductor resistance
4) collector inductor resistance
5) transistor
6) LED
7) output CSR

If (P1+P2+P3+P4+P5+P6+P7) > Pin, then 

If (P1+P2+P3+P4+P5+P6+P7) </= Pin, then 

Yes, that's true. When looking for over unity, the power dissipated by all the circuit components plus the power dissipated by the load is the total power consumed, but practically we really want to know what overall efficiency we can get with respect to the output load power, since the load power is the useable power, although a really inefficient circuit could maybe be used to help warm a room in the winter, or to power a peltier module. Actually, these days where battery life in mobile devices is quite important, I wonder if any manufacturers have started using peltier modules to convert heat produced by the circuitry back to electricity? Maybe the efficiency gains involved wouldn't make it worth the extra component cost however.

[Void]

@Lawrence: Here are my measurements for your board #119, using your scope probe measurement method.
I didn't compensate for the voltage drop across the one ohm current sensing resistor at the input in my Excel calculations, but you can do that if you wish by modifying the attached Excel file. I am still seeing that odd variation in my efficiency measurements, and I am still investigating to see if I can figure out what might be causing it, so all I can say for now is this is what I measured for your board # 119 right at the current moment.

Input Voltage: 0.5VDC regulated supply
Input Power:   5.195mW
Output Power: 4.159mW
Efficiency:       80.06%

Scope screen shots and Excel files used for power calculations are attached.
Yellow traces are voltage and blue traces are current.
Input current waveform is inverted.

[Void]

@Lawrence: Here are my measurements for your board #118, using your scope probe measurement method.

Input Voltage: 0.5VDC regulated supply
Input Power:   4.893mW
Output Power: 3.765mW
Efficiency:       76.95%

Scope screen shots and Excel files used for power calculations are attached.
Yellow traces are voltage and blue traces are current.
Input current waveform is inverted.

[Void]

@Lawrence: Here are my measurements for your board #134, using your scope probe measurement method.
The other three boards you sent me do not light up. I would need to take a look at them to see what the issue is.

Input Voltage: 0.5VDC regulated supply
Input Power:   4.994mW
Output Power: 4.023mW
Efficiency:       80.56%

Scope screen shots and Excel files used for power calculations are attached.
Yellow traces are voltage and blue traces are current.
Input current waveform is inverted.

[TinselKoala]

http://touchstonesemi.com/products/current-sense-amplifiers